Research

Early chimpanzee experiments ran the gamut—from infecting them with virtually every infectious agent known, to using them in head crash and trauma studies, or as unwilling donors for organ transplants.

Chimpanzees were irradiated to see the effects on their bodies. They were injected with brain tissue from patients with schizophrenia and multiple sclerosis, or with pulverized brain tissue from humans who died from kuru. Infant chimpanzees were separated from their mothers and put in isolation chambers to observe their responses.

Few limits, if any at all, were placed on what was done to them by scientists.

History vs. today

In recent years, the general public, lawmakers and scientists expressed increasing discomfort over the use of chimpanzees in biomedical research, ultimately culminating in the National Institute of Health's decision to no longer fund such research.

Some particularly egregious experiments on chimpanzees unfortunately persisted until relatively recently. For more information, read Experiments: Current Overview.

The following summarizes the types of experiments endured by chimpanzees from 1950 to 1985 in the U.S. (Click here for a detailed list of past experiments.)

Invasive procedures

Chimpanzees have suffered many invasive procedures, including some which

Removed or destroyed portions of their brains to test brain function

Killed them and removed their organs (hearts, kidneys, livers) to be used for human transplants (all of which failed)

Exposed them to huge doses of radiation causing significant damage

Castrated and removed their pituitary glands, followed by hormone analysis

Placed electrodes into their brains

Poisoning

Chimpanzees have been used to test the toxicity of insecticides, chemicals, and pharmaceutical drugs. Drug testing continues today, even though such research may be dangerous for determining drug safety in humans.

Chimpanzees were used extensively by Fred Coulston, a toxicologist, to study chemical carcinogens. A 1979 grant by the National Institutes of Health describes how the project would subject chimpanzees to various carcinogens, radiation, and oncogenic viruses.

Large doses of interferons [proteins derived from human cells which have antiviral properties] were administered to chimpanzees to test side effects and toxicity.

Alcohol was infused into chimpanzees inoculated with hepatitis B to test whether it would induce liver damage.

Physical trauma

Chimpanzees have been subjected to severe physical trauma and killed by the U.S. Air Force for air and space travel research. They were crashed at supersonic speeds, burned in wind blast experiments, and spun in centrifuges. Read more: Air & Space.

In separate experiments, researchers subjected chimpanzees to severe head trauma, high impact, and whiplash. Others exposed them to adverse conditions like rapid decompression to a state of near vacuum or gravitational forces while submerged in water.

Mental trauma

In behavioral and cognitive experiments, toddler chimpanzees have been subjected to severe isolation—in some cases for up to four years. Baby chimpanzees were taken from their mothers despite the fact that in the wild they would spend many years living together and would not be weaned before age five.

In cross-fostering and language experiments, chimpanzees have been raised in a family setting and sometimes taught to communicate with humans using sign language only to be later abandoned to research labs or zoos when they became too large and strong to handle.

Infectious and fatal diseases

Chimpanzees have been infected with almost every major disease known to kill humans including typhoid, ebola, kuru, malaria, and Creutzfeldt-Jakob.

Even after being infected with pathogens, in many instances chimpanzees do not become ill, or if they do, their illness is often milder and more self-limiting than the human form of the disease. When chimpanzees do become ill, researchers document the chimpanzees’ decline in health. Chimpanzees may not be given painkillers or other medication to relieve any symptoms because scientists are concerned about interfering with results.

Chimpanzees as bioreactors

Chimpanzees were used extensively today as incubators to grow vaccines for viruses that are difficult to grow in culture medium. The most notable example of this is the use of chimpanzees to develop a vaccine for the hepatitis B virus (HBV).

This “achievement” is often referenced by the scientific world in support of its continued use of chimpanzees in research. However, the chimpanzees were not used as models for the physiology of the disease for which there is still no cure. There is no basis to argue that without their use a vaccine would not have still been developed.

Reproduction/sex

Chimpanzees have been favored by scientists for use in reproductive physiology research. This research began as an exploration of more efficient means for breeding them in captivity to ensure a ready supply.

Historic reproductive research on chimpanzees has typically been invasive, especially for female chimpanzees. Surgery has been used liberally to explore the ovaries and progression of embryos and fetuses in the female reproductive tract. As one grant abstract from 1977 states: “Details of spermatozoon migration through the chimpanzee female reproductive tract, obtained by experiments inadmissible in man, should provide an indication of the time course of similar events in the human female.” (NIH Grant 5R01RR000992-02 “Artificial Breeding of Chimpanzees,” Emory University 1976-77)

Male chimpanzees have suffered the ways developed to obtain semen—from surgeries to invade the testes, to being taught to masturbate on demand, to being subjected to electroejaculation (a process in which a probe is inserted into the rectum and electrical stimulation applied to force ejaculation).

Drug dosing and addiction

Chimpanzees have been dosed with a range of drugs—including nicotine, cocaine, morphine, and marijuana—to test their reactions.

In an experiment to test the effects of morphine on behavior, two chimpanzees and three baboons were given varying doses via intramuscular injections while being tested on key-pressing in response to food rewards. One chimpanzee died during these experiments when he stopped breathing due to morphine overdose.

The same researcher conducted a similar experiment on chimpanzees using increasing doses of cocaine. Convulsive seizures resulted at higher doses of cocaine injection.

Unwilling organ donors

Three American surgeons used organs from chimpanzees to transplant into humans. In each case, the surgeries were conducted largely in secret to sidestep the moral issues that abounded.

In 1964, a sole attempt was made in the United States to transplant the heart of a chimpanzee into a human. It was an utter failure and generated considerable controversy over the ethics of killing highly sentient primates.

A NOTE ABOUT THE INFORMATION AVAILABLE IN THIS REPORT:

Information concerning what happens to animals in biomedical research is not readily available to the public and must be gleaned from limited information. The information compiled in this section was obtained primarily through published papers in scientific journals and abstracts for federal grants under the Computer Retrieval of Information on Scientific Projects (CRISP) online database. Little information is available on experiments that are funded by private companies.

Interpreting information obtained from these limited sources is difficult. If you have information that adds to or conflicts with any provided on this site, we welcome your feedback.